1. Field of the Invention
The present invention generally relates to an electrophotographic image-forming apparatus such as a printer and a facsimile machine.
2. Description of the Related Art
A conventional electrophotographic image-forming apparatus is of the configuration as shown in FIG. 1. A charging roller 2 charges the surface of a photoconductive drum 1. A light source 3 illuminates the charged surface of the photoconductive drum 1 in accordance with print data to form an electrostatic latent image. A developing roller 4 applies, for example, toner to the electrostatic latent image to develop the electrostatic latent image into a visible image. A toner-supplying roller 5 charges the toner and supplies the charged toner to the developing roller. A developing blade 6 forms a toner layer having a uniform thickness on the developing roller 4. A transfer roller 7 transfers the toner image from the photoconductive drum 1 onto a recording medium. A cleaning blade 8 collects residual toner remaining on the photoconductive drum that failed to be transferred onto the recording medium. Sealing members 9 are pressed against the circumferential surface of longitudinal end portions of the developing roller 4 to seal against the toner from leaking through the gaps in the vicinity of the longitudinal ends of the developing roller 4. The sealing member 9 effectively reduces the surface roughness of the developing roller 4 so that the toner is difficult to leak. Alternatively, a cylindrical film is attached to the longitudinal end portions of the developing roller 4 to prevent toner leakage.
However, the sealing members 9 pressed against the longitudinal end portions of the developing roller 4 are not sufficient and some toner still leaks. If the sealing member 9 is firmly pressed against the developing roller 4 prevents the toner leakage but the friction between the developing roller 4 and sealing members 9 increases. Thus, the force that presses the sealing members 9 should be limited.